An integrated circuit (IC) is a miniaturized electronic circuit including semiconductor devices and passive components and which is manufactured in and on the surface of a substrate typically formed of semiconductor material. Integrated circuits are used in a variety of devices and a multitude of applications due to their low cost and high performance.
A high number of integrated circuits are fabricated simultaneously on a semiconductor substrate. Once the integrated circuits are completed, the semiconductor substrate is sawed into individual chips. The uppermost surfaces of the chips are generally protected by a passivation layer disposed over the integrated circuit. This passivation layer, however, cannot cover the periphery of each chip. Thus, the periphery of each chip is exposed to undesirable moisture and ionic contaminants. Accordingly, guard rings or seal rings as they are alternatively called, are commonly formed around at least the upper periphery of the chip as part of the integrated circuit fabrication process, prior to sawing the substrate. Seal rings are formed of one or multiple metal layers and can provide structural reinforcement and stop undesirable moisture and mobile ionic contaminants from entering chip active circuitry regions and affecting operational reliability. The structural stability of the seal ring has become increasingly important with the advent of extremely low-k, ELK, dielectrics which can be very porous in nature.
Features that can provide structural stability to the seal ring structures are metal vias and other metal structures formed at different device levels. The structures formed in seal rings are not active device structures and are often referred to as dummy metal structures. It is desirable for seal rings to be coupled to ground.